This investigation is in the 4th year of its second 5-year cycle. The primary aim of the present study is to examine differences between 3 groups of patients and healthy controls on laboratory measures of pain sensitivity and in brain regional cerebral blood flow (rCBF) during (a) resting conditions and (b) a 5-minute exposure to painful mechanical pressure stimulation. The 3 patient groups consist of right-handed women with (a) fibromyalgia, (b) chronic fatigue syndromes, and (3) major depression. Patients are carefully screened to eliminate overlap in these diagnoses across groups. We primarily have studied patients with fibromyalgia and health controls, to date. However, we now have new referral sources for patients with chronic fatigue syndrome and major depression. Thus, we anticipate completing all subject studies by December, 2001.